MAMMALIA. 435 
‘mune also existed on the Isle of Wight. Another species is mentioned as 
peculiar to the Sivalik Mountains in Asia. 
The genus Xiphodon is composed of one species of Anoplotherium, the 
light and slender form of which seems to indicate great agility, comparable 
only to that of the gazelle and the roe. The tail is short and slender. 
* The genus Dichobune, with the same essential characters, is of the size 
of the hare, with the same proportion between the anterior and posterior 
limbs, which according to all probability gave to them a similar walk. 
Three species occur in the tertiary basin of Paris, and a fourth is peculiar 
to England. 
The genus Oplothertwm exhibits great affinities with Anoplotherium, and 
more especially with Dichobune, but differs by an essential character; the 
canines, which in the preceding genera are searcely to be distinguished 
from the incisors, are prominent and curved like those of the tapirs and 
Paleotherium. Species of this genus have been found in France and 
Germany. The genus Microtherium was established upon one of them. 
The genus Macrauchenta combines in a remarkable manner the forms 
of the camel and Paleeotherium. The head and teeth are yet unknown; 
but the vertebrz of the neck indicate that this region of the body was 
elongated, as in the lama. The legs or limbs resemble those in ruminants, 
but the feet are constructed as in pachyderms. The only species known 
was found in Patagonia, south of St. Julian harbor. Its size was nearly 
equal to that of the rhinoceros and hippopotamus of our days. 
The genus Chalicotherium is known only by its dentition, which indicates 
an affinity with Anoplotherium. Two species have been found in the 
meiocene deposits of Germany, whose bulk, it is supposed, reached that of 
the rhinoceros. 
The genus Cainotherium we merely mention here. It is but little known. 
In the opinion of some it is the same as Chalicotherium, and in that of 
others the same as Oplotherium. Two species, we are told, have been 
found in the eocene deposits of France. 
Fam. 2. HIPPOPOTAMID#, or PACHYDERMATA PROPER, in the actual fauna, 
generally comprehends clumsy and colossal beings the limbs of which are 
very short, the hind feet with three and the fore feet with three or four 
hoofed toes. The hoofs themselves are of irregular forms, as in the follow- 
ing family, and all of them rest on the bottom. For this reason there are 
no posterior rudimentary toes. The dentition exhibits both analogies and 
affinities with the other families of the order. The incisors are either want- 
ing or vary in number from two to six. Canines seldom exist, and where 
they happen to be present their length is not disproportioned. The molars 
are generally seven in each jaw, sometimes only six in the lower, exhibiting 
various forms. The few living genera, with equally few species, inhabit the 
warmer parts of both the old and new worlds. Fossil remains of species 
belonging to the recent genera, together with others belonging to genera 
entirely extinct, have been found in the tertiary beds of America, Europe, 
and Asia. 
The genus Hippopotamus is characterized by a very massive and naked 
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